We are interested in the nature of the interactions between RNA polymerase and DNA which lead to the initiation of transcription, and in the interactions between ribosomes and mRNA which lead to the initiation of translation. Additionally, we are concerned with the means by which those interactions are regulated, positively and negatively, by other components of the cell. We study bacteriophage T4-infected Escherichia coli; our focus is entirely on two specific T4 genes (genes 32 and rIIB). We isolate and characterize mutants which alter the transcription or translation of one (or both) of those genes. The characterization of mutants is performed both in vivo and in vitro. At the completion of this project we should understand, in molecular detail, the primary events which control some of the temporal and quantitative patterns of gene expression. Our work on the genetics of initiation of translation has allowed us to consider protein-like three-dimensional structures of mRNA which are recognized by ribosomes.